Field of Art
The present disclosure relates to a technique for forming an image on a recording medium using an electrophotographic method.
Description of the Related Art
Electrophotographic image forming apparatuses are known. Such an image forming apparatus forms an electrostatic latent image by emitting light onto a photosensitive member on the basis of image data, applies a developer to the electrostatic latent image (performs development), transfers and fixes the image to a recording medium such as a recording sheet, and outputs the recording medium. Representative examples of such an image forming apparatus include a laser beam printer and an LED printer. In such an image forming apparatus, at the time of the emission of a light beam or the formation of an electrostatic latent image, image degradation occurs. The contrast of a latent image potential formed on a photosensitive member decreases at that time. The relationship between a latent image potential on a photosensitive member and the amount of toner applied as a developer at the time of development is nonlinear, and is affected by the decrease in the contrast of a latent image potential. In the case of image data including a thin character or a thin line, the contrast of a latent image potential easily decreases and the thinning or detail loss of a line occurs at the time of formation of an image. The reproducibility of an output image therefore decreases.
Japanese Patent Laid-Open No. 2000-36912 or 2009-105943 discloses a technique for controlling the line width of input image data to improve the reproducibility of an output image. More specifically, a line width in image data is detected by referring to the image data of a portion around the edge of a thin line and the gradation value of the edge is changed using the amount of correction corresponding to the detected line width, so that the thin-line reproducibility of an output image is improved. With the technique disclosed in Japanese Patent Laid-Open No. 2000-36912 or 2009-105943, the amount of correction is changed in accordance with a line width in image data. It is therefore considered to be possible to faithfully reproduce a thin line on an output image on the basis of the image data.
However, the technique disclosed in Japanese Patent Laid-Open. No. 2000-36912 or 2009-105943, in which the image data of a portion around the edge of a thin line is referred to for the detection of the width of the thin line, requires a large hardware circuit size and a high calculation cost.